The present invention relates to probes which can be used to image or determine compositional information from structures using radiation with a frequency from 0.1 THz to 84 THz. The present invention also relates to a method for studying diseased teeth.
Recently, there has been much interest in using THz radiation to look at a wide variety of samples using a range of methods. THz radiation can be used for both imaging samples and obtaining spectra at each pixel in an image. THz radiation penetrates most dry, non-metallic and non-polar objects like plastic, paper, textiles, cardboard, semiconductors and non-polar organic substances. Therefore, THz radiation can be used instead of x-rays to look inside boxes, cases etc. THz has lower energy non ionising photons compared to x-rays, hence, the health risk of using THz radiation are expected to be vastly reduced compared to those using conventional x-rays.
The use of THz imaging for medical purposes has been suggested. However, it is believed that the penetration depth of THz radiation might hinder imaging deep inside the human body. Also, as the human body contains a large amount of water, and water is known to be a strong absorber of THz radiation, this will also affect the useful imaging depth which can be obtained using THz radiation. Moreover, even dehydrated tissue types such a dry skin have limited penetration depths. For example, at 2.0 THz, α˜35 cm−1 for moist dermis whereas α˜29 cm−1 for dry dermis. The 1 mW average power levels that are now available suggest that only about 4 mm of moist dermis could be probed using THz.